In a modern communications network, most teleservices require a frequency difference or a phase difference between network-wide devices to be kept within an appropriate error range for normal running, that is, have a network clock synchronization requirement. Clock synchronization includes frequency synchronization and phase synchronization. Frequency synchronization indicates that a specific strict relationship is kept between frequencies or phases of signals, that is, a constant phase difference is kept between the signals within a relatively small range, for example, less than 100 nanoseconds. Currently, main clock synchronization technologies include the Institute of Electrical and Electronics Engineers (IEEE) 1588v2 and Synchronous Ethernet (SyncE). SyncE is used to implement frequency synchronization, and IEEE 1588v2 is mainly used to implement time synchronization, that is, phase synchronization. A base station in a third generation (3G) or later-generation mobile network obtains a clock synchronization signal from a bearer network of the base station to perform frequency synchronization and time synchronization. Normal synchronization and normal service running in the mobile network can be ensured only when clock synchronization is implemented on all devices in the bearer network.
In a mobile bearer network, for example, a packet transport network (PTN), or an Internet Protocol (IP) radio access network (RAN), in a process in which a device in the mobile bearer network needs to perform networking and interconnection with a device in another network, clock asynchronization may exist between the two interconnected devices. Currently, whether a problem of clock asynchronization exists is determined by manually analyzing clock synchronization signals of two interconnected devices and/or manually analyzing a faulty node on a clock synchronization path. Therefore, efficiency is relatively low. The foregoing clock synchronization problem also exists in another communications network that has a stringent delay requirement, for example, a power control network, or a low-delay Ethernet compliant with IEEE 802.1AS.